Apparatus for producing packets

ABSTRACT

An apparatus for attaching a tag and a thread length to a web of filter material with one end of the thread length secured to the tag and the other end being secured to the web adjacent one side edge of the web and the tag being attached to the web adjacent the opposite side edge. The apparatus has a gripper for drawing the tag, with the thread secured thereto, across the web from that one edge to an extended position beyond the opposite side edge before returning the tag to a final extended position over the web. The apparatus also has a mechanism for attaching the tag to the web in the final position, a displacement mechanism for the gripper means that has a first linear guide on which the gripper is slidable, and a second inner guide that is transverse to the first guide and fixedly located in the apparatus. The gripper is movable in the mutually transverse directions of the guides, both transversely across the web to the extended and final positions and longitudinally of the web away from the tag-attaching mechanism.

[0001] This invention relates to apparatus for the production of taggedpackets, such as infusion bags, in which a tag and thread length isattached to the bag envelope of filter material to allow the bag to besuspended from the tag in use.

[0002] When producing such tagged packets it is generally undesirable toallow the tag to hang free from the bag by its thread because when anumber of such packets are packaged together the threads can easilybecome entangled. Generally, therefore, the tag is temporarily attachedto the bag in addition to securing the end of the thread remote from thetag permanently to the bag.

[0003] A simple way of placing the thread is lay it across the filtermaterial while it is still a flat web, attaching the tag near one sideedge and securing the opposite end of the thread near the other sideedge. In this arrangement, however, the width of the web determines thelength of the thread and that length may be undesirably limited. Inorder to provide an ample length of thread it is known to give thethread a convoluted pattern on the web, but the mechanisms to producesuch patterns are relatively complicated.

[0004] It is also known to increase the length of the thread by drawinga tag attached to one end of the thread across the web to an extendedposition beyond the side edge of the web, thus returning to tag to afinal position over the web near that side edge to attach it to the web.Although the additional length is obtained by a simple rectilinearmovement, if it is required to attach the tag to the web on or near theline of the thread, it is necessary to ensure that the tag drawing meansdoes not clash with the tag-web attaching means.

[0005] According to one aspect of the present invention, apparatus isprovided for attaching a tag and length of thread length to a web offilter material, one end of the thread being secured to the tag and theother end being secured to the web adjacent one side edge, and the tagbeing attached to the web adjacent the opposite side edge, the apparatuscomprising gripper means for drawing the tag beyond said opposite sideedge before returning the tag to a final extended position over the web,and means for attachment of the tag to the web in said final position, adisplacement mechanism for said gripper means comprising a first linearguide on which the gripper means is slidable, and a second linear guidetransverse to said first guide on which said first guide is slidable,said second guide being fixedly located in the apparatus, whereby thegripper means is movable in the mutually transverse directions of theguides, both transversely across the web to said extended and finalpositions and longitudinally of the web away from the tag-attachingmeans.

[0006] In this manner a relatively simple and robust mechanism can beprovided that will lay the extended length of thread across the web andalso begin the return movement of the gripper means past thetag-attaching means by guiding the gripper means longitudinally of theweb to clear the attaching means.

[0007] Preferably, said first linear guide extends transversely acrossthe web and said second linear guide on which the first guide isslidable extends longitudinally of the web.

[0008] The use of the form-fill process for producing filled packets iswell known, the packet filter material in the form of a continuous webbeing shaped into a tube around a forming tube through which the fillingmaterial is provided and, as it is drawn off the tube, transverse sealsbeing made to form it into separate compartments which are separated toyield the individual packets. It is also known to make the transverseseals and separate the packets by traversing an ultrasonic sealingdevice across the flattened tubular web and back.

[0009] According to a further aspect of the present invention, thesealing and separating process is accelerated without incurring anysignificant additional costs by performing the cutting and sealingoperation over the width of the tubular web in a single pass wherebysuccessive packets are sealed closed and separated by displacements ofthe ultrasonic sealing device in opposite directions.

[0010] The sealing device can be located on a rotary mounting thatpivots coaxially to the forming tube to perform successive cutting andsealing operations in mutually transverse directions, so producingtetrahedral-like packets.

[0011] By way of example, an embodiment of the invention will now bedescribed with reference to the accompanying diagrammatic drawings, inwhich:

[0012]FIG. 1 is a side view of a machine for producing tagged tea bagswhich incorporates the invention,

[0013]FIG. 2 is a side view to a larger scale of the tag-thread unit ofthe machine in FIG. 1 showing the tag and thread supply means,

[0014]FIG. 2a shows schematically the tag to thread attachment process,

[0015]FIG. 3 is a plan view of the tag path to the filter web in thetag-thread unit,

[0016]FIG. 3a is an enlarged detail of the circled area Z in FIG. 3,

[0017]FIG. 4 is a plan view further illustrating the tag path over theweb in the tag-thread unit,

[0018]FIG. 5 is a plan view of the mechanism carrying the leadinggripper for drawing the tag over the filter web,

[0019]FIGS. 6 and 7 show the cam drives for the gripper mechanism inFIG. 5, for movement longitudinally and transverse to the webrespectively,

[0020]FIGS. 8 and 9 illustrate in plan and from the front respectively,the ultrasonic sealing devices for attaching a tag-thread assembly tothe web,

[0021]FIG. 8a is a detail illustration of thread cutting device on thethread sealing device,

[0022]FIG. 10 illustrates schematically the packet forming process inthe inner bag unit of the machine,

[0023]FIGS. 11 and 12 are plan view and a side sectional view on theline XII-XII of the web transverse cutting and sealing mechanism,

[0024]FIG. 13 is a plan view of the rotary drive for the cutting andsealing unit, and

[0025]FIG. 14 is a graphical illustration of the sealing and cuttingoperations in the inner bag unit.

[0026]FIG. 1 is an overall view of the bag-forming machine. It has threemain units. Firstly, a tag-thread unit A where tags are attached atspaced positions along a thread and each tag is then attached with alength of the thread to a web of filter material from which the bags areto be formed. The web leaves the tag-thread unit with a series ofseparate tag-thread assemblies applied across it at spaced intervalsalong its length (as indicated in FIG. 8), and is led to an inner bagunit B which comprises a form-fill apparatus in which the web is firstformed into a tube and the tube is then sealed transversely to give aseries of discrete compartments which are separated into the individualbags. The third main unit is a dosing unit C above the bag unit whichsupplies doses of tea or other filling material to the form-fillapparatus to be deposited in the filter tube before each compartment issealed closed.

[0027] The filter web W, of a porous plastic material capable of beingsealed ultrasonically, is supplied from a reel 12 mounted in a holder 14in the tag-thread unit A. The web path is shown leading over a roller 16on a tensioning arm 18 and subsequently over a rear roller 20 (FIG. 4)to a horizontal track region 22 in the unit where the tag-threadassemblies are applied to the web, before it passes over the exitrollers to the inner bag unit B.

[0028] A tag-thread attachment module 24 in the unit A is offsetlaterally from the web path. Tags T are supplied to in a continuousstrip from a reel 26 mounted on a holder 28, as shown to a larger scalein FIG. 2. The tag strip is drawn from the reel to the module by a pairof pinch rollers 30 in a stepped feed. With each step, one tag length ofthe strip is located in an ultrasonic sealing device 32, to be grippedbetween a horn 34 and anvil 36 of the sealing device. In the path of thetag strip, immediately upstream of the sealing device 32 is a cutter 38comprising cooperating upper and lower shear blades 40, 42. The thread Sis drawn from a spool 44, through a thread guide 46 to the sealingdevice 32 where it is guided laterally into a groove 48 in the sealingdevice anvil 36 to lie across the foremost tag length of the tag stripin the sealing device.

[0029] In operation, when the leading tag of the tag strip has beenlocated in the sealing device 32, over the thread in the anvil groove48, the horn 34 and anvil 36 of sealing device are closed together togrip the tag and thread, and the horn is energised to secure them toeach other. Immediately this has occurred, the cutter 38 is operated tosever the tag from the tag strip.

[0030] In a manner described in more detail below, the tag, with theattached thread, is drawn from the attachment module 24, transversely tothe plane of FIG. 2, in two steps. In the first step the tag at thesealing device is drawn along a tag chute 52 (FIGS. 3 and 4) to the endof the chute at the right-hand edge of the web as shown in FIG. 4 forexample. In the second step, also shown in FIG. 4, the tag is drawnacross the filter web, while the thread remains in a continuous lengthextending from the spool 44, to an extended left-most position. Thesemovements are obtained by gripping the foremost tag with a leadinggripper 56 that is displaceable across the width of the web. Between thetwo successive steps, a further tag is secured to the thread in theattachment module 24 by the sealing device 32 in the manner alreadydescribed. As each tag is brought to an extended position beyond thewidth of the web, the following tag thus emerges from the tag chute andis held by a retaining gripper 58 before being engaged by the leadinggripper in its next cycle of movement.

[0031]FIG. 4 illustrates these displacements of the tag transversely tothe web. The leading gripper has a right-most home position close to afixed position occupied by the retaining gripper 58. The retaininggripper first engages each tag when it has been drawn through the tagchute from the tag-thread sealing device. The leading gripper then takesover the tag to draw it to the left-most extended position. At thatpoint, the required length of the thread has been drawn through thetag-thread attachment module for the next tag to be attached to thethread in that module. When the leading gripper has returned to the homeposition the cycle can therefore be repeated.

[0032]FIG. 4 shows further details of the movement of the leadinggripper 56. When the leading gripper takes over a tag from the retaininggripper 58 it moves over a straight path 60 a from its home positionclose to the retaining gripper, to the extended position which liesbeyond the left-hand edge of the web. The movement to the extendedposition has brought the next tag over the right-hand edge of the weband the retaining gripper now closes to hold it fixed there. The leadinggripper begins a return movement, also along the path 60 a, that placesthe tag over the web, near its left-hand edge, where the tag is securedto the web as will be further described below. The gripper is then ableto release the tag and is moved rearwards over the path 60 b a shortdistance to allow it to continue its return movement across the web,along a path 60 c parallel to its rectilinear path over the web. Finallyit makes a short forward movement over path 60 d bringing it to its homeor starting position where the succeeding tag is held by the retaininggripper. The leading gripper can now take that tag over from theretaining gripper to repeat the cycle of movement.

[0033] The opening and closing movements of the jaws of the leading andretaining grippers 56, 58 and the movements of the leading gripper 56over the filter web, are generated by a series of cams on a common camshaft 62 shown only fragmentarily. Also, although not illustrated, themotions of the mechanisms in the tag-thread attachment module can beproduced by further cams on the same cam shaft or a further cam shaftrotating in synchronism with the cam shaft 62. Two cams on the cam shaftcontrol the movement of the leading gripper 56 in the directionstransverse to the web and longitudinally of the web respectively. Asseen in FIG. 6, a cam 64 for the longitudinal movement acts on afollower lever 66 spring-loaded against the cam. The lever 66 movesabout a fixed lower pivot 68. The upper end of the lever is connected bya link 70 to a table 72 supported in fixed guides 74 extending in thelongitudinal direction of the web. The gripper 56 is mounted on acarriage 76 held in a linear guide 78 extending along an edge of thetable 72, transversely to the web, so that the gripper 56 and table 72reciprocate together in the longitudinal direction under the action ofthe first cam 64.

[0034] For the movement of the gripper carriage along its guidetransverse to the web, as shown in FIG. 7, a second cam 82 acts on ahorizontal lever 84 having a rear fixed pivot 86. The forward end of thelever 84 is connected by a link 88 to a bell crank lever 90 having apivot axis 92 extending in the longitudinal direction of the web. Abiasing spring 94 acting on the bell crank lever 90 urges the followerlever 84 against the cam. The upper arm of the bell crank lever 90 isconnected to the gripper carriage 76 by a drive rod 96. Although notillustrated, the drive rod 96 is jointed to allow the gripper carriage70 to accommodate the movements with the table 72 in the longitudinaldirection generated by the first cam 64. The gripper jaws are operatedby a further drive rod (not shown) which is similarly jointed andoperated by another cam (not shown) on the cam shaft 62.

[0035] As already mentioned, the tag is secured to the web after it hasbeen returned from the extended position to lie over the web. Referringto FIGS. 8 and 9, two ultrasonic sealing devices 102, 104 eachcomprising a sealing horn 106 and anvil 108, secure the tag and itsthread at locations close to the respective side edges of the web W. Thehorns 106 and the anvils 108 each have their own drive mechanisms (notshown) operated by further cams on the cam shaft 62. Adjacent theright-hand sealing device 104 and operating in synchronism with thatdevice are a supplementary thread clamp 110 having upper and lower jaws112, 114 fixed relative to the sealing device horn 106 and anvil 108respectively. Also mounted on the right-hand sealing device horn 106 isa thread cutting blade 114. The thread cutting blade 116 cooperates witha fixed counter-plate 118 which lies over the right-hand margin of theweb.

[0036] The operations of the sealing devices 102, 104 and the retaininggripper 58 are coordinated with the movements of the leading gripper 56in the following manner by the cams on the cam shaft 62. As the leadinggripper draws a tag and its thread across the web, the sealing devices102, 104 and the retainer gripper 58 are held open. As the leadinggripper 56 reaches its extended position, with the thread drawn taut,the retaining gripper 58 is closed. The right-hand sealing device 102has already begun to close; its horn 106 and anvil 108 remain apart atthis point, but the adjacent thread clamp 110, which is spring loaded,grips the thread and web so that the length of thread under the cuttingblade 116 is kept in the taut state unaffected by the return movement ofthe leading gripper and tag which now begins, as also does the closingmovement of the left-hand sealing device 102.

[0037] As the tag is brought into the zone of left-hand sealing device102, the horn 106 and anvil 108 of the device close to clamp the tag andthe leading gripper 56 opens. Meanwhile the right-hand sealing device104 has already closed and, in the final stage of its movement, thecutter blade 116 has severed the thread and has come to rest in a slot122 in the counter-plate 118. The energisation of the ultrasonic sealinghorns 106 after each sealing device 102, 104 has closed secures thethread permanently to the web near its left-hand edge and attaches thetag releasably to the web near its left-hand edge, as indicated by thesealing zones 124 a, 124 b in FIG. 8.

[0038] As it releases its tag, the leading gripper 52 is retractedrearwards, to follow its return path clear of the adjacent sealingdevice as the sealing operation proceeds. The right-hand sealing device104 begins to open before the gripper 56 comes abreast of the device butthe left-hand device 102 is opened only as the gripper 56 completes itsreturn movement to the home position. Initiating the next cycle ofmovement, the leading gripper 56 now closes on the succeeding tag whichis thereupon released by the retaining gripper 58.

[0039] With the opening of the sealing devices 102, 104 the filter webcan be stepped forward, and the cycle is then repeated. During thesealing of the tag and thread to the web, as already described, afurther tag has been attached to the thread and severed from the tagstrip at the attachment module 24 while the foremost tag-thread assemblywas being secured to the web. This further tag, with its attached threadis then drawn along the tag chute with the movement of the next tagacross the web.

[0040] The web W, with the tag-thread assemblies attached to it, is ledto the inner bag unit C where the filled packets are produced by aform-fill process. As the flat web is drawn downwards in steppedmovements through the inner bag unit by rollers 142, 144 (FIG. 10), itis shaped over a guide 146 and around a forming tube 148 to bring theopposite side edges together progressively and those edges are thenjoined by an ultrasonic sealing device 150 to give the web a closedtubular cross-section with the tag-thread assemblies on its outer facebefore it leaves the forming tube. As will be understood, the steppeddrive of the rollers 142, 144 is synchronised with the rotation of thecam shaft 62.

[0041] Below the forming tube a transverse sealing mechanism 152 makestransverse seals across the tube at regular intervals and separates theindividual packets formed by each successive pair of seals. In sequencewith the transverse sealing of the tubular web, the dosing unit Bdispenses doses of tea or other filling material through the formingtube 148, so that each packet receives a dose of material before it issealed closed. In the illustrated example, successive transverse sealsare rotationally offset at 90 ÿ to each other about the axis of theforming tube and tubular web, so giving the packets a tetrahedral-likeshape.

[0042] The dosing unit B can be of conventional form. Similarly, themeans for giving the web its closed tubular form, need not be describedin further detail. FIGS. 11 and 12, however, illustrate features of thetransverse sealing and cutting mechanism 152.

[0043] The mechanism comprises a ring-form base plate 154 on whichparallel guides 156 are secured to mount a pair of clamping jaws 158 a,158 b. A pair of air cylinders 160 are secured to opposite ends of afirst of the jaws 158 a, between the jaw and fixed brackets 162 on thebase plate 154. A sprocket wheel 164 is mounted on each bracket and foreach sprocket there is a chain (not shown) secured at one end to thefirst jaw 158 a, and passing around 180 y of the sprocket to a returnlength that is secured to the second jaw 158 b. The two jaws are therebycoupled together, so that the operation of the air cylinders 160 movesboth jaws equal and opposite distances.

[0044] The mechanism 152 is provided with an ultrasonic sealing devicecomprising a horn 170 extending through an elongate slot 172 the firstjaw and a cooperating anvil 174 provided by the opposed face of thesecond jaw. The horn 170 is coupled to a yoke 176 which is supported ona pair of guide tubes 178 extending between the brackets 162. Apistonless cylinder 180, also secured between the brackets 162 has adrive collar 182 coupled to the yoke 176 to displace the horn along theslot in the jaw 158 a. The sealing horn 170 is also connected to its jaw158 a to move with it and is coupled to the drive collar 182 through asleeve 184 in which the horn is slidable to permit movement transverseto the cylinder 180. The second jaw 158 b also has a slot 186 along itslength, in the centre of the anvil face. Projecting through that slot isa pressure wheel 188 connected to the yoke 176 through a spring-loadedmounting 188 urging the wheel 188 towards the horn 170.

[0045] With the clamping jaws 158 a, 158 b open, the horn 170 iswithdrawn from the anvil 172 and the anvil wheel 188 projects slightlyfrom the second jaw 158 b. When the clamping jaws close, the horn comesclose to the outer face of the anvil 172 and applies pressure to thewheel 188. In this state, when the sealing horn 170 is energised,movement of the horn 170 and wheel 188 along their slots in the clampingjaws by the operation of the cylinder 180, severs the web across itswidth and simultaneously seals the web across its width at each side ofthe line of severance.

[0046] The base plate 154 is mounted on a turntable 190 to be rotatablecoaxially to the forming tube by a servo-motor 192 coupled to theturntable by a toothed belt 194, drive control means (not shown)actuating the turntable to make successive 90 ÿ rotations in oppositedirections in synchronism with the rotation of the cam shaft 62. Asensor 196 for the turntable 190 rotation provides a datum position forthe servo-motor drive control means. Over-limit switches 198 areprovided at positions beyond the normal angular movement of theturntable 190 to stop the turntable drive if tripped by a cam block 200carried by the turntable. The required rotation of the turntable canthus be generated simply and economically.

[0047] The sequence of operation of the transverse cutting and sealingmechanism is shown graphically in FIG. 14 against a time base. Thediagram in FIG. 11 shows at I the movement of the clamping jaws, at IImovement of the sealing device along the jaw slots, at III toenergisation of the sealing horn, at IV the rotation of the turntable,and at V the feed of the tubular web through the mechanism.

[0048] In the first stage, the cylinders 160 close the clamping jaws 158a, 158 b, as shown at a, together to flatten and clamp the cylindricalweb between them in a region spaced from the tag-thread assemblies. Theultrasonic sealing horn 170 is then energised, as shown at b, and thecylinder 180 operated, as shown at c, to move the horn 170 and wheel 188across the width of the web completing the sealing and separation of apacket and forming the bottom seal of the next packet to be produced.The clamping jaws are then opened, as shown at d. The turntable 154 cannow be rotated through 90 ÿ, as shown at e, while the web is advancedthe length of a packet, as shown at f. The clamping jaws close again, asshown at g, which is followed by a return traverse movement of thesealing device, as shown at h, with energisation of the horn as shown ati, the next sealing and cutting operation. The jaws open again, as shownat j, and the rotation of the turntable is reversed, as shown at k, asthe next web length is fed through the mechanism, as shown at l, afterwhich the cycle can be repeated.

What is claimed is:
 1. Apparatus for attaching a tag and a thread lengthto a web of filter material with one end of the thread length secured tothe tag and the other end being secured to the web adjacent one sideedge of the web and the tag being attached to the web adjacent theopposite side edge, comprising gripper means for drawing the tag, withsaid thread secured thereto, across the web from said one edge to anextended position beyond the opposite side edge before returning the tagto a final extended position over the web, and means for attaching thetag to the web in said final position, a displacement mechanism for saidgripper means comprising a first linear guide on which the gripper meansis slidable, and a second inner guide transverse to said first guide onwhich said first guide is slidable, said second guide being fixedlylocated in the apparatus, whereby the gripper means is movable in themutually transverse directions of the guides, both transversely acrossthe web to said extended and final positions and longitudinally of theweb away from the tag-attaching means.
 2. Apparatus according to claim 1wherein said first linear guide extends transversely across the web andsaid second linear guide extends longitudinally of the web.
 3. Apparatusaccording to claim 2 wherein a cam drive is provided to control saidmovements of the gripper means.
 4. Apparatus according to claim 3wherein respective cams are provided for the displacements of thegripper means and its guide in the mutually transverse directions. 5.Apparatus according to claim 1 wherein the tag attaching means comprisesa sealing member and an opposed anvil between which the web and tag areclamped to be sealed together, a further sealing member and anvil beingprovided for attaching the thread adjacent said one side edge of theweb, and respective drive means are provided for each sealing member andanvil for performing said attachment adjacent each side edgeindependently of the other.
 6. Apparatus according to claim 5 whereinthe attachment of the thread adjacent said one side edge is arranged tobe completed before said attachment of the tag to the web.
 7. Apparatusaccording to claim 6 comprising means between said sealing members andanvils but nearer said one side edge of the web for clamping the threadto the web when the thread has been drawn to said extended position andbefore the gripper means has returned to said final position. 8.Apparatus according to claim 1 comprising holding means for engagementwith the thread beyond said thread length and adjacent said one edge ofthe web when the tag has been drawn to its extended position.
 9. Packetforming apparatus comprising a forming tube and means for drawing a webof packet material along the tube to a cylindrical shape and means forsealing together opposite edges of the web to form a closed tube,transverse sealing and cutting means in the path of the web beyond theforming tube for forming a series of individual packets, the transversesealing and cutting means comprising a pair of opposed jaws forflattening the web between them and sealing and cutting meansdisplaceable across the flattened web for severing the web and sealingthe edges to each side of the line of severance, the clamping means andthe cutting and sealing means being mounted on a rotatable base so thateach successive of the web is rotationally offset from the precedingseverance with respect to the axis of the tubular web, each said cuttingand sealing operation across the width of the web being made in a singlepass whereby successive packets are sealed closed and separated bydisplacements of said sealing and cutting means in opposite directions.10. Apparatus according to claim 9 wherein a rotary drive motor iscoupled to the turntable for rotation of the turntable in oppositedirections for the successive cutting and sealing operations, theturntable carrying means providing a datum for said servo motor drive.